Breathing valve assembly with diaphragm control of the exhaust ports

ABSTRACT

A breathing apparatus having an exhaust valve and a diaphragm actuated inlet valve, wherein the exhaust valve includes a sealing surface against which the diaphragm normally is sealingly engaged to close the opening and from which the diaphragm is disengaged upon exhalation to open the exhaust valve.

BACKGROUND OF THE INVENTION

(a) Field of the Invention

This invention relates to breathing apparatus of the type whereinbreathing fluid is provided to a mask upon a demand evidenced byinhalation by the user of the mask.

(b) History of the Prior Art

In the prior art, demand type valves for use in conjunction withbreathing masks have been provided which are responsive to inhalation bythe mask user. In one type of such mask a flexible member in the form ofa diaphragm moves in response to the reduced pressure created in themask chamber upon inhalation and actuates a lever which in turn opens abreathing fluid supply valve. Such masks, as shown in the prior artcustomarily are provided with an independent exhaust valve which opensupon exhalation to permit the escape of gas exhaled by the mask user.The exhaled gas both moves the diaphragm to its normal position of restand opens the independent exhaust valve.

BRIEF DESCRIPTION OF THE INVENTION

In accordance with the invention there is provided demand type breathingapparatus wherein the exhaust valve and the diaphragm are combined thuseliminating the need for an independent exhaust valve. The diaphragmcontrols both the inlet and the exhaust valves, opening the former inresponse to inhalation and the latter in response to exhalation.

The breathing apparatus of the invention comprises a hollow casing whichis provided with an opening in the casing wall. A flexible diaphragm ispositioned across the opening and in conjunction with the hollow casingforms a chamber. The diaphragm is movable in response to variations indifferential pressure between the inside and outside of the chamber. Abreathing fluid inlet valve communicates with the chamber and is openedin response to inward movement of the diaphragm resulting from areduction of chamber pressure created upon inhalation by a user of theapparatus. An outlet valve is provided for exhausting fluid from thechamber when pressure within the chamber is increased above apredetermined value upon exhalation by the user.

The improvement of the invention comprises providing a sealing surfaceagainst which the diaphragm normally is sealingly engaged and from whichat least a portion of the diaphragm is disengaged upon exhalation intothe chamber. The diaphragm and the sealing surface act as the outletvalve with the diaphragm controlling both the inlet valve and theexhaust ports, thereby eliminating the need for a separate outlet orexhaust valve.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a side elevational view of a breathing mask equipped with abreathing valve assembly of this invention.

FIG. 2 is a sectional view of the breathing valve assembly, on anenlarged scale.

FIG. 3 is a further enlarged, fragmentary sectional view of the exhaustvalve in a partially open position.

FIG. 4 is similar to that of FIG. 3 showing the exhaust valve in afurther open position.

DETAILED DESCRIPTION OF THE INVENTION

Referring now in detail to the embodiment depicted by way ofillustration in the accompanying drawing, there is shown a breathingapparatus 10 which comprises a casing 11, a flexible diaphragm 12 and acover 13. The casing may be made of any suitable rigid material which isessentially impervious to air and oxygen, such as steel, aluminum andrigid plastics, and which will not incorporate toxic substances intobreathing fluids. The casing is defined by a casing wall 14 throughwhich a first opening 15 is provided. Flexible diaphragm 12 havinginternal and external surfaces 16 and 17 respectively is positionedacross opening 15. Flexible diaphragm 12 is manufactured from a flexiblegas impervious material such as natural or silicone rubber or a flexibleplastic.

Flexible diaphragm 12 in conjunction with casing 11 defines a chamber 18into which a breathing fluid supply line 19 is connected through aninlet valve 20 of conventional design. Breathing fluid supply line 19 isconnected to a source of breathing fluid, not shown, such as air oroxygen. Inlet valve 20 is opened in response to inward movements ofdiaphragm 12 by a tilt lever 21 which is moved by diaphragm 12 to openinlet valve 20 and which has a restoring spring 25 to close the valveupon outward movement of the diaphragm, all in a manner well known inthe demand regulator art.

The apparatus is provided with an outlet valve 22 for venting orexhausting fluid from chamber 18 when fluid pressure within chamber 18exceeds a predetermined level. A second opening 23 into chamber 18 isprovided which is adapted for airtight communication with the breathingfunction of a user, usually through a close coupling to breathing mask30 as shown. If desired, such communication can be through a tube orhose, not shown, one end of which is tightly connected with secondopening 23 and the other end of which is connected to breathing mask 30.

In accordance with the invention, there is provided a sealing surface 24about opening 15 against which a circumferential portion 28 of internalsurface 16 of diaphragm 12 normally sealingly engages to close opening15 and from which at least a portion of diaphragm 12 is disengaged whenthe pressure within the chamber 18 increases above a predeterminedlevel, thus permitting surface 16 of diaphragm 12 in conjunction withsurface 24 to act as outlet valve 22.

Casing wall 14 is formed to provide an exhaust channel 31 around opening15, communicating with chamber 18 when diaphragm 12 is disengaged fromsurface 24 and closed from communication with chamber 18 when diaphragm12 sealingly engages surface 24. Channel 31 is vented to atmospherethrough ports 27' at the bottom of the channel, and is subdivided intoan annular series of exhaust ports 27 by an annular series of radialbars 32 joined at their outer periphery by a ring 33 having a recessedbottom wall providing an annular chamber 34 communicating with exhaustports 27 and with vent ports 27'. Bars 32 are of substantial width orthickness, and with ring 33 provide an inwardly sloping, invertedfrusto-conical support surface 57 for the circumferential portion 28 ofdiaphragm 12 when it is sealing engaged against surface 24 to closeoutlet 22, as shown in FIG. 2. The slope of surface 57 is such that itsinner periphery is only slightly below the sealing surface 24 of casingwall 14, and its outer periphery is at diaphragm ring 26 orsubstantially so.

External surface 17 of diaphragm 12 is protected by cover 13 which isshaped to provide a chamber 29 on the side of diaphragm 12 oppositechamber 18 and which is provided with a vent 40 so that external surface17 of flexible diaphragm 12 is usually constantly exposed to atmosphericpressure. Periphery 26 of diaphragm 12 is a thick ring securely held inthe recessed upper ends of casing wall 14 and of ring 33 by cover 13 butdiaphragm 12 is not held against sealing surface 24 by cover 13.

The diaphragm 17 is carefully designed so that in any orientation thereis a preload built into a diaphragm sufficient to maintain contact withthe sealing surface 24 with no differential pressure across thediaphragm. This means that a small positive pressure in chamber 18 mustbe induced to lift the diaphragm at sealing surface 24 and exhaust theexhaled gases through ports 27, 27'.

In its most common usage, the gas in chamber 29 simply moves in and outthrough port 40 as the differential pressure across diaphragm 12 isaltered by an induced negative or positive pressure in chamber 18. It iswithin the scope of the invention, however, that a positive pressure(above ambient) may be imposed on the diaphragm by some secondarydevice, as described below. However, the design is such that thedifferential pressure across diaphragm 12 needed to either open thedemand valve 20 or in turn to lift diaphragm 17 from sealing edge 24 toexhaust gases, will remain almost constant. This is accomplished by theradial supports 32, 33 which are incorporated in exhaust channel 31, sothat the effective area of the diaphragm subject to the differentialpressure remains in a substantially constant ratio of 1:1.

When the regulator is of the pressure-demand type, to avoid anypossibility of inboard leakage for example, an orificed flow of gas fromthe upstream side of inlet valve 20 to chamber 29 can be provided. Asshown in FIG. 2, cover 13 can have a passage 50 communicating withchamber 29 and with a passage 56' in casing 11 communicating with theinlet supply. Casing 11 also has a bore 56 communicating with passage56' and containing an orifice button 52 having a restricted orifice 53communicating with passage 56' through a filter 54. The opposite ends ofbore 56 are sealed around passages 50 and 56' by O rings 51 and 55. Withthis arrangement a constant supply of inlet gas is bled to chamber 29,biasing diaphragm 12 to maintain a positive pressure in chamber 18 in amanner known in the art. An aneroid 37 in a cap 35 on cover 13 carries avalve 38 adapted to engage a seat 39 around port 40, the cap having ventopenings 36 to atmosphere. Port 40 and valve 38 are of a diameterapproximately equal to the diameter of aneroid 37, whereby aneroid 37and the pressure in chamber 29 act against the same valve area.

Support surface 57 is useful but not essential when operating in thestraight demand mode and diaphragm 12 is subject only to ambientatmospheric pressure in chamber 29. When operating in the pressuredemand mode, however, supporting surface 57 is necessary to maintain thedesired uniform opening action of outlet 22 in response to increasedpressure on surface 16 of diaphragm 12.

In operation, when the user of apparatus 10 inhales, the pressure withinchamber 18 is reduced which causes the center of diaphragm 12 to moveinwardly, activating lever 21 which in turn opens inlet valve 20 thuspermitting breathing fluid to enter chamber 18. This reinforces theself-sealing action of diaphragm 12 against surface 24, keeping outletvalve 22 closed. When the user of breathing apparatus 10 exhales, thepressure in chamber 18 is increased and diaphragm 12 moves outwardlypermitting inlet valve 20 to close. However, outlet valve 22 remainsclosed and circumferential portion 28 of diaphragm 12 does not lift awayfrom sealing surface 24 until the pressure within chamber 18 exceedsthat within chamber 29 by an amount sufficient to overcome the built-inpreload or self-sealing bias of diaphragm 12 whereupon diaphragm portion28 is lifted from supporting surface 57 permitting exhaled gas to passbetween internal surface 16 of diaphragm 12 and sealing surface 24through exhaust ports 27 and vents 27' to the outside of apparatus 10.The amount of diaphragm portion 28 which is lifted from surface 57increases with the pressure force of exhalation, thereby increasing thearea of exhaust opening through ports 27 as shown by comparing FIGS. 3and 4.

Thus, the inlet valve actuating diaphragm 12 also controls the exhaustoutlet. The inlet 20 is opened by the diaphragm upon inhalation to admitbreathing fluid to the chamber, the outlet 22 remaining closed by thediaphragm. The outlet is opened by the diaphragm upon exhalation, afterpermitting the inlet to close, to vent the products of exhalation fromthe chamber. The diaphragm 12, in conjunction with the peripheralsealing surface 24 provides the outlet valving action. The truncated,inverted conical shape of surface 57 supports diaphragm portion 28, atrest and during inward movement of the diaphragm, and also duringlifting of portion 28 away from surface 24 upon outward movement of thediaphragm.

I claim:
 1. In a breathing apparatus .Iadd.capable of operating in thepressure demand mode and .Iaddend.having a hollow casing with an openingin one wall thereof, a flexible diaphragm .Iadd.having a relatively thinannular portion, the diaphragm being .Iaddend.secured at its peripheryrelative to said casing and having internal and external surfaces.Iadd.subject to fluid pressure and .Iaddend.positioned across saidopening, said diaphragm forming a chamber in conjunction with saidcasing and being movable in response to variations in differentialpressure across said diaphragm, a breathing fluid .Iadd.supply, an.Iaddend.inlet .Iadd.valve connecting said fluid supply .Iaddend.to saidchamber, means for opening said inlet .Iadd.valve .Iaddend.responsive tomovement of said diaphragm inwardly of said chamber upon a reduction ofpressure within said chamber, .Iadd.a breathing port from said chamberadapted to be connected to a user, .Iaddend.a fluid outlet from saidchamber, .[.and.]. means for opening said outlet when .Iadd.the.Iaddend.pressure within said chamber exceeds the .Iadd.pressure bearingupon the external surface by .Iaddend.a .Iadd.relatively constant.Iaddend.predetermined .[.relative pressure.]. .Iadd.overpressure, andpressure maintaining means capable of maintaining the fluid pressurebearing upon the external surface of said diaphragm at a relativelyconstant pressure while the inlet and outlet are sequentially opened andclosed; .Iaddend.the improvement wherein said means for opening.Iadd.said outlet .Iaddend.comprises arranging said diaphragm and saidoutlet so that .Iadd.the relatively thin annular portion of.Iaddend.said diaphragm .[.itself.]. normally closes said outlet andmaintains said outlet closed until the chamber pressure .[.exceeds apredetermined value.]. .Iadd.attains said overpressure.Iaddend.whereupon movement of said diaphragm outwardly of said chamberopens said outlet to vent fluid from said chamber.Iadd., together withsupporting means adjacent said outlet for supporting the relatively thinannular portion of said diaphragm so that the effective area of theinternal and external surface of said diaphragm subject to differentialpressure remains in a substantially constant ratio as said diaphragmopens said outlet whereby the overpressure necessary to open saiddiaphragm remains substantially constant even though the flow rate andpressure may vary. .Iaddend.
 2. Breathing apparatus as defined in claim1, said apparatus .[.being of the straight demand type.]. .Iadd.alsobeing capable of operating in the straight demand mode.Iaddend.. 3.Breathing apparatus as defined in claim 1, said .[.apparatus being ofthe pressure-demand type.]. .Iadd.supporting means causing saideffective area of said diaphragm to remain in a substantially constantratio of 1:1.Iaddend..
 4. Breathing apparatus as defined in claim 1,said means for opening said inlet including a tilt valve having a stemengaged by said diaphragm upon inward movement thereof to open saidvalve and spring means biasing said valve to .Iadd.an .Iaddend.inletclosing position.
 5. Breathing apparatus as defined in claim 1,.[.together with.]. .Iadd.in which .Iaddend.a sealing surface is.Iadd.is disposed adjacent said outlet and .Iaddend.about said opening.[.against which.]..Iadd., .Iaddend.a portion of the internal surface ofsaid diaphragm normally .[.sealing engages to close.]. .Iadd.engagingsaid sealing surface to close .Iaddend.said outlet and from which atleast a portion of said diaphragm is disengaged when the pressure withinsaid chamber exceeds a predetermined value, said diaphragm and surfacethereby acting as an outlet valve.
 6. Breathing apparatus as defined inclaim .[.5.]. .Iadd.1 .Iaddend., said diaphragm having a built-inpre-load sufficient to maintain said outlet valve normally closed in allpositions of orientation of said apparatus.
 7. In a breathing apparatus.Iadd.capable of operating in the pressure demand mode and.Iaddend.having a hollow casing with an opening in one wall thereof, aflexible diaphragm .Iadd.having a relatively thin annular portion, thediaphragm being .Iaddend.secured at its periphery relative to saidcasing and having internal and external surfaces .Iadd.subject to fluidpressure and .Iaddend.positioned across said opening, said diaphragmforming a chamber in conjunction with said casing and being movable inresponse to variations in differential pressure across said diaphragm, abreathing fluid .Iadd.supply, an .Iaddend.inlet .Iadd.valve connectingsaid fluid supply .Iaddend.to said chamber, means for opening said inlet.Iadd.valve .Iaddend.responsive to movement of said diaphragm inwardlyof said chamber upon a reduction of pressure within said chamber, afluid outlet from said chamber .[.and.]..Iadd., a breathing port fromsaid chamber adapted to be connected to a user, .Iaddend.means foropening said outlet when pressure within said chamber exceeds .Iadd.thepressure bearing upon the external surface by .Iaddend.a.Iadd.relatively constant .Iaddend.predetermined .[.relative pressure.]..Iadd.overpressure, and pressure maintaining means capable ofmaintaining the fluid pressure bearing upon the external surface of saiddiaphragm of a relatively constant pressure while the inlet and outletare sequentially opened and closed; .Iaddend.the improvement whereinsaid means for opening .Iadd.said outlet .Iaddend.comprises arrangingsaid diaphragm and said outlet so that .Iadd.the relatively thin annularportion of .Iaddend.said diaphragm .[.itself.]. normally closes saidoutlet and maintains said outlet closed until the chamber pressure.[.exceeds a predetermined value.]. .Iadd.attains said overpressure.Iaddend.whereupon said diaphragm opens said outlet to vent fluid fromsaid chamber, .Iadd.together with supporting means adjacent said outletfor supporting said annular portion of said diaphragm so that theeffective area of the internal and external surfaces of said diaphragmsubject to differential pressure remains in a substantially constantratio as said diaphragm opens said outlet, and .Iaddend.wherein said.[.external surface of said diaphragm is protected by.]. .Iadd.pressuremaintaining means includes .Iaddend.a cover defining with said diaphragma second chamber, said second chamber .Iadd.protecting the externalsurface of said diaphragm and .Iaddend.being vented to the exterior ofsaid apparatus.
 8. Breathing apparatus as defined in claim 7, saiddiaphragm having a built-in pre-load sufficient to maintain said outletvalve normally closed in all positions of orientation of said apparatus.9. Pressure-demand breathing apparatus as defined in claim 7, togetherwith means for maintaining a positive pressure within said secondchamber relative to ambient atmosphere.
 10. Pressure-demand breathingapparatus as defined in claim 9, wherein said means for maintaining apositive pressure include a bleed passage from said inlet to said secondchamber, and .Iadd.an .Iaddend.aneroid .[.means.]. controlling the ventfrom said second chamber.
 11. Pressure-demand breathing apparatus asdefined in claim 9, said outlet comprising .[.a.]. .Iadd.an annular.Iaddend.series of .[.alternating.]. ports .[.and support.]..Iadd.,supporting .Iaddend.means .[.around said opening.]. .Iadd.consisting ofan annular series of radial bars separating said ports.Iaddend., and.[.a.]. .Iadd.an annular sealing surface .[.around.]. .Iadd.adjacent.Iaddend.said .Iadd.outlet .Iaddend.inwardly of said ports and.[.suppport.]. .Iadd.supporting .Iaddend.means, said internal surface ofsaid diaphragm normally .[.sealing.]. .Iadd.sealingly .Iaddend.engagingsaid sealing surface to close said outlet, said .[.support.]. supportingmeans providing support for .Iadd.the relatively thin annular portion of.Iaddend.said diaphragm outwardly of said sealing surface .Iadd.so thatthe differential pressure across said diaphragm needed to lift saiddiaphragm from said sealing surface will remain almost constant tomaintain the desired substantially uniform outlet opening action..Iaddend.
 12. In a breathing apparatus .Iadd.capable of operating in thepressure demand mode and .Iaddend.having a hollow casing with an openingin one wall thereof, a flexible diaphragm .Iadd.having a relatively thinannular portion, the diaphragm being .Iaddend.secured at its peripheryrelative to said casing and having internal and external surfaces.Iadd.subject to fluid pressure and .Iaddend.positioned across saidopening, said diaphragm forming a chamber in conjunction with saidcasing and being movable in response to variations in differentialpressure across said diaphragm, a breathing fluid .Iadd.supply, an.Iaddend.inlet .Iadd.valve connecting said fluid supply .Iaddend.to saidchamber, means for opening said inlet .Iadd.valve .Iaddend.responsive tomovement of said diaphragm inwardly of said chamber upon a reduction ofpressure within said chamber, a fluid outlet from said chamber.[.and.]..Iadd., a breathing port from said chamber adapted to beconnected to a user, .Iaddend.means for opening said outlet whenpressure within said chamber exceeds .Iadd.the pressure bearing upon theexternal surface by .Iaddend.a .Iadd.relatively constant.Iaddend.predetermined .[.relative pressure.]. .Iadd.overpressure, andpressure maintaining means capable of maintaining the fluid pressurebearing upon the external surface of said diaphragm of a relativelyconstant pressure while the inlet and outlet are sequentially opened andclosed; .Iaddend.the improvement wherein said means for opening.Iadd.said outlet .Iaddend.comprises arranging said diaphragm and saidoutlet so that .Iadd.the relatively thin annular portion of.Iaddend.said diaphragm normally closes said outlet and maintains saidoutlet closed until the chamber pressure .[.exceeds a predeterminedvalue.]. .Iadd.attains said overpressure .Iaddend.whereupon saiddiaphragm opens said outlet to vent fluid from said chamber, togetherwith a sealing surface .Iadd.extending .Iaddend.about said opening.Iadd.and through which said outlet extends and .Iaddend.against which aportion of the internal surface of .Iadd.the annular portion of.Iaddend.said diaphragm normally sealingly engages to close said outletand from which at least a portion of said diaphragm is disengaged whenthe pressure within said chamber exceeds a predetermined value, saiddiaphragm and said .Iadd.sealing .Iaddend.surface thereby acting as anoutlet valve, said outlet comprising a series of alternating ports and.[.support.]. .Iadd.supporting .Iaddend.means .[.around said opening,.]..Iadd.in .Iaddend.said sealing surface .[.being interposed between saidseries of outlet ports and said opening, and said opening.]., and said.[.support.]. .Iadd.supporting .Iaddend.means providing support for.Iadd.the relatively thin annular portion of .Iaddend.said diaphragm.[.outwardly of said sealing surface.]. .Iadd.so that the effective areaof the internal and external surfaces of said diaphragm subject todifferential pressure remains in a substantially constant ratio as saiddiaphragm opens said outlet whereby the differential pressure acrosssaid diaphragm needed to lift said diaphragm from said sealing surfacewill remain almost constant, thereby providing the desired outletopening action..Iaddend.
 13. Breathing apparatus as defined in claim 12,said apparatus being of the pressure-demand type having means formaintaining a positive pressure relative to ambient atmosphere on saidexternal surface of said diaphragm. .Iadd.14. Breathing apparatus asdefined in claim 1, said flexible diaphragm being so shaped that whenthe outlet is opened it is not necessary to stretch said diaphragm, therelatively thin portion of the diaphragm rolling away from said outlet..Iaddend.